Repetition priming effects from attended vs. ignored single words in a semantic categorization task

The present research examines priming effects from a centrally presented single-prime word to which participants were instructed to either attend or ignore. The prime word was followed by a single central target word to which participants made a semantic categorization (animate vs. inanimate) task. The main variables manipulated across experiments were attentional instructions (attend vs. ignore the prime word), presentation duration of the prime word (20, 50, 80 or 100 ms), prime–target stimulus onset asynchrony (SOA; 300 vs. 800 ms), and temporal presentation of instructions (before vs. after the prime word). The results showed (a) a consistent interaction between attentional instructions and repetition priming and (b) a qualitatively different ignored priming pattern as a function of prime duration: reduced positive priming (relative to the attend instruction) for prime exposures of 80 and 100 ms, and reliable negative priming for the shorter prime exposures of 20 and 50 ms. In addition (c), the differential priming pattern for attend and ignore trials was observed at a prime–target SOA of 800 ms (but not at a shorter 300-ms SOA) and only when instructions were presented before the prime word. Methodological and theoretical implications of the present findings for the extant negative priming literature are discussed.